General information on the use of geothermal energy

By human standards geothermal energy is an inexhaustible source of energy. When drilling down from the earth's surface to deeper layers, the temperature for the first 100m remains almost stable at approximately 10°C. After that the temperature increases by an average of 3°C per every 100m depth. The heat emanated at this depth is called geothermal heat which can be harvested for energy production purposes by means of different procedures.

There are three main processes to harvest geothermal heat: near-surface geothermal systems (down to a depth of 400m), geothermal systems harvesting warm underground water (down to a depth of 4500 m) and systems, which also extract heat from deep rock layers for power generation (also called EGS or enhanced geothermal systems by experts) with drilling currently down to a depth of 5000m.

Current figures on geothermal energy for power generation: BMU brochure "Renewable energy sources in figures".

The new Renewable Energies Heat Act entered into force on 1 January 2009. It introduced an obligation for new buildings to use renewable energy to cover heating requirements. Geothermal energy can be used to fulfil this obligation, using e.g. heat pumps in combination with near-surface thermal heat or district heat sources from deeper geothermal layers.

Near-surface geothermal energy / heat pumps

Near-surface geothermal heat is harvested by using heat pumps. A heat pump can supply a building with energy for heating, cooling and warm water. This geothermal energy system is also open to use by private households. Efficient heat pumps are funded under the market incentive programme (in German).

Deep geothermal energy

Geothermal installations for power generation are funded by the Federal Government under the Renewable Energy Sources Act (EEG). The EEG grants a high degree of planning and investment security due to fixed tariffs over a period of 20 years. Electricity providers are entitled to feed-in tariffs for the electricity generated from the relevant grid operator (utilities).

Moreover, funds from the market incentive programme (in German) are available for installations harvesting deep geothermal energy for electricity and/or heat generation purposes.

Research funding by the Federal Environment Ministry also plays an important role in the field of deep geothermal energy. Information on the main focus of German research funding can be found in the Government's current notice of call for proposals (in German) .